Gas leak detectors for fluid systems have been used, such as the leak detector shown in U.S. Pat. No. 3,583,435. Such leak detectors are particularly useful in gas systems which utilize high pressure butane or propane gas containers, for example, but not limited to, mobile homes, boats, campers, and the like. The leak detectors not only minimize waste of gas, but, more importantly, detect small leaks and hazardous leaks. It is essential that the leak detector be easily and quickly operated to encourage frequent tests, and at the same time be an absolutely positive device regarding the existence of a leak. The leak detector described by U.S. Pat. No. 3,583,435 can be partially operated by pushing only part way on the operating button allowing gas to continue flowing normally. The operator may, however, think the detector is actually testing for leaks when it is not.
The time of flow at the normal low pressures of 1/2 to 1 psig is another weakness in a spring loaded, push-button detector actuator which returns to the line flow position automatically rather than a shut off position. The detector actuator must be held in place until the entire system is filled. This can be 10 to 15 seconds for an average system, and fatigue may cause the operator to relax the pressure on the button allowing gas to continue flowing into the system and perhaps resulting in an undetected leak.